LOANS - Corporate Loan Delinquency (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Non-Accrual Details
Loans, net of unearned income	$ 644,695	$ 624,369
Loans at fair value	4,216	3,486
Corporate
Non-Accrual Details
90 days past due and accruing	1,115	997
Total non-accrual	2,098	2,421
Total current	312,032	292,431
Loans, net of unearned income	319,434	299,306
Loans at fair value	4,189	3,457
Purchased distressed loans	$ 0	0
Number of days past due, non-accrual status	90 days
Loans less than this number of days past due are considered current	30 days
Corporate | Commercial and industrial
Non-Accrual Details
90 days past due and accruing	$ 311	195
Total non-accrual	1,521	1,909
Total current	136,229	127,012
Loans, net of unearned income	138,061	129,116
Corporate | Financial institutions
Non-Accrual Details
90 days past due and accruing	477	121
Total non-accrual	232	185
Total current	70,355	61,254
Loans, net of unearned income	71,064	61,560
Corporate | Mortgage and real estate
Non-Accrual Details
90 days past due and accruing	158	285
Total non-accrual	186	139
Total current	48,462	43,607
Loans, net of unearned income	48,806	44,031
Corporate | Leases
Non-Accrual Details
90 days past due and accruing	67	35
Total non-accrual	63	56
Total current	1,571	1,678
Loans, net of unearned income	1,701	1,769
Corporate | Other
Non-Accrual Details
90 days past due and accruing	102	361
Total non-accrual	96	132
Total current	55,415	58,880
Loans, net of unearned income	55,613	59,373
Corporate | 30 to 89 Days Past Due
Non-Accrual Details
90 days past due and accruing	963	786
Corporate | 30 to 89 Days Past Due | Commercial and industrial
Non-Accrual Details
90 days past due and accruing	233	143
Corporate | 30 to 89 Days Past Due | Financial institutions
Non-Accrual Details
90 days past due and accruing	438	119
Corporate | 30 to 89 Days Past Due | Mortgage and real estate
Non-Accrual Details
90 days past due and accruing	146	148
Corporate | 30 to 89 Days Past Due | Leases
Non-Accrual Details
90 days past due and accruing	59	27
Corporate | 30 to 89 Days Past Due | Other
Non-Accrual Details
90 days past due and accruing	87	349
Corporate | Equal to greater than 90 days past due and accruing
Non-Accrual Details
90 days past due and accruing	152	211
Corporate | Equal to greater than 90 days past due and accruing | Commercial and industrial
Non-Accrual Details
90 days past due and accruing	78	52
Corporate | Equal to greater than 90 days past due and accruing | Financial institutions
Non-Accrual Details
90 days past due and accruing	39	2
Corporate | Equal to greater than 90 days past due and accruing | Mortgage and real estate
Non-Accrual Details
90 days past due and accruing	12	137
Corporate | Equal to greater than 90 days past due and accruing | Leases
Non-Accrual Details
90 days past due and accruing	8	8
Corporate | Equal to greater than 90 days past due and accruing | Other
Non-Accrual Details
90 days past due and accruing	$ 15	$ 12